1. Field of the Invention
The invention relates to the field of video conferencing, and more particularly to the field of virtual classroom video conferencing over a network data connection.
2. Discussion of the State of the Art
Video Conferencing has become an important component of virtual online learning. Universities, Colleges and Schools are increasingly using the Internet to deliver courses and curricula to geographically remote students while commercial and other types of organization are similarly using these tools to provide live, instructor-led training to employees, customers, distributors, volunteers etc. Web cams have become more generally available as built-in devices in laptop computers and tablets (plug-in units are also available for many computing devices at costs that are within reach of everyone), they can now be considered to be ubiquitous.
Similarly, technology is now widely available to make video web conferencing available to everyone using tools like Skype™ and Google Video™ Chat, through to sophisticated “virtual classrooms” using commercial products such as Adobe Connect, WebEx™, Elluminate™, GoToMeeting™, BigBlueButton™ and many others.
All of the tools mentioned allow users at their option to “share” their camera with others in the “virtual classroom” and some systems allow the technology to highlight or focus on the participants who have most recently been speaking. It is well known that between 60% and 90% of human communication is nonverbal and in a traditional physical classroom setting the teacher or trainer is able to “read” this information as they stand at the front of the class delivering the lesson. They are able to see which students are listening, confused, bored, engaged, distracted etc. and can call on one or more students based on this nonverbal feedback. Students in this environment should be focused entirely on the teacher and the class materials unless they are engaged in a discussion with the instructor or an interaction with other students. There are however, two major issues associated with the aforementioned tools related to virtual live, instructor-led classrooms.
As the number of video feeds being shared, rises, the number of simultaneous connections tends to rise exponentially. With two cameras publishing a feed and each user subscribing to the other's feed, there are a total of four connections. With three cameras, the virtual classroom needs to support nine concurrent feeds and with twenty cameras, the number of feeds rises to four hundred. Each user in a virtual classroom with N cameras is publishing a single feed and playing back N−1 feeds from the other cameras requiring the system to support N2 feeds.
For online classes of 5 to 250+ students, the mathematics quickly result in an overwhelming amount of bandwidth and an overwhelming challenge for the students' computers to receive and render the incoming videos. As a consequence of this, previous attempts to deal with this issue tend to reduce the quality and frame-rate of the video streams with rising numbers of cameras but this rapidly eliminates the value of the live video as it transforms in to a series of poor quality still frames that update infrequently. Many technologies limit the number of simultaneous cameras to fewer than ten cameras for this reason and for those that do not have a physical limit, the practical limit is typically fewer than twenty feeds.
A second issue with increasing numbers of simultaneous video feeds is that the screen real-estate required to display the video images quickly reduces the amount of space available within the virtual classroom left to present class materials or for other elements such as chat, screen sharing, slide shows, documents, recorded video, whiteboards etc. While having multiple cameras visible to everyone in the virtual classroom makes sense for a small group chat scenario or to allow every student to see their peers, in many cases in an educational or training setting this is only a temporary requirement or can be distracting. From the teacher's perspective the need is quite different.